1. Field of the Invention
The present invention relates to a telephone system with a clock and more particularly to a telephone system with a clock which produces a time announcing tone at a preset time.
2. Description of the Background Art
A conventional telephone system with a clock capable of setting a desired time comprises, in addition to a telephone generally used, a hold state setting circuit for putting a connection over a transmission line on hold, a clock, a time setting key for setting a time, a circuit for detecting the set time, and a tone generator which generates a tone for announcing the hold state or the time when the hold state is set or the set time arrives.
In the above described telephone system with the clock, if the user operates the time setting key to set a desired time, the time detecting circuit automatically detects the set time when the set time arrives and in response to the detection output the tone generator generates a time announcing tone. This makes sure that the user is informed of the arrival of the set time to do a prescribed thing, for example, to make a call to a certain person.
However, the above described conventional telephone system involves a disadvantage that if the set time arrives while the connection state of the transmission line is on hold, it is not possible to inform the user of the arrival of the set time since the tone announcing the arrival of the set time and the tone indicating the hold state are identical. Accordingly, it might happen that the user has forgotten to do the scheduled thing at the desired time and for example the user can not leave a message to a specified person. In addition, also in the case where the hold state is set and the holding tone is generated while the time announcing tone is emitted, the user can not determine whether the generated tone is the time announcing tone or the hold state indicating tone.
If a call is received and a calling tone is emitted while the time announcing tone is emitted at the arrival of the set time, the time announcing tone and the calling tone overlap, making it difficult for the user to be aware of the reception of the call.